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This invention relates generally to the field of tension devices and more specifically to a self-locking and adjustable apparatus for changing and maintaining the length and tautness of a serpentine article.
Adjustable tension devices for a serpentine article has many applications including tie-down cords, belts, straps, rigging, and tourniquets. These devices have found uses in homes and in the entertainment, sporting, travel, marine, medical, and other industries.
Easy adjustability and secure gripping have been sought after features of adjustable tension devices. The amount of tautness a tension device will maintain before it slips or breaks depends not only upon the tensile strength of the serpentine article but also the design and composition of the device.
A patented adjustable tension device utilizing an elastic cord in a loop configuration is the invention of Libecco, U.S. Pat. No. 6,389,655 B2, May 2002, ADJUSTABLE ELASTIC TIE-DOWN CORD. The prior art of Libecco""s invention is illustrated in FIG. 1. The ADJUSTABLE ELASTIC TIE-DOWN CORD consists of an adjusting retainer bar, two hooks, and an elongated elastic cord. Elastic cord 11 originates at stop knot 12, passes through passage 13, forms an adjustable loop to which hook 14 is attached, passes through passage 15 that has protrusions, and terminates in a non-adjustable loop that has hook 16 attached. The length and tautness of the tie-down cord is adjusted by sliding cord 11 through passage 15 in retainer bar 10. The protrusions provided in passage 15 engage and penetrate the stretch cord for assisting and locking it in position within the passage.
A patented buckle for adjusting the length and tautness of a serpentine article is the invention of Plzak, U.S. Pat. No. 6,295,700, October 2001, BUCKLE FOR MAINTAINING TENSION IN A SERPENTINE ARTICLE. The prior art of Plzak""s invention is illustrated in FIG. 2. The BUCKLE FOR MAINTAINING TENSION IN A SERPENTINE ARTICLE consists of pin 20, first cam load bearing portion 21, second cam load bearing portion 22, first structure load bearing portion 23, second structure load bearing portion 24, serpentine article 25, axis of rotation 26, cam 27, handle 28, and channel 29 in handle 28. To adjust the tension on serpentine article 25, serpentine article 25 is passed through the circuitous route within the buckle. Tension on serpentine article 25 causes cam 27 to rotate clockwise around axis 26 and pinch serpentine article 25 between (1) the first cam 21 and first structure 23 load bearing portions, and between (2) second cam 22 and second structure 24 load bearing portions. Handle 28 attaches to cam 27. Channel 29 in handle 28 provides space for the passage of serpentine article 25. To release the tension on serpentine article 25, handle 28 is depressed. Cam 27 rotates on pin 20.
The deficiencies of the ADJUSTABLE ELASTIC TIE-DOWN CORD of Libecco are (1) the strength of the grip is limited to the strength of the protrusions within the passage in the retainer bar, (2) the diameter of the holes in the retainer bar must be closely matched with the diameter of the cord because the protrusions must penetrate the cord to lock it into position, (3) the protrusions restrict sliding and hinder cord adjustments, (4) the protrusions penetrate the cord and may damage and weaken the cord, and (5) when the two hooks are under tension, the line of force is through channel 15 and not through the center of the loop, this causes the retainer bar to pivot which may lead to instability of the tension device.
The deficiencies of the BUCKLE FOR MAINTAINING TENSION IN A SERPENTINE ARTICLE of Plzak are as following. (1) The rotary cam is a key feature of Plzak""s invention. Because it is movable, the buckle has the problems inherent of moving parts, particularly since the parts are exposed to environmental conditions. Dust and debris can collect between the cam and the pin with potential malfunction of the moveable cam. Depending upon the composition of the pin, salt water may corrode the pin when made of metal and cause the cam to malfunction. (2) The multiplicity of weight bearing parts, cam 27, housing structures 23 and 24, and pin 20, increases the number of items that are subject to wear and damage by the stress of heavy loads as compared to a tension device constructed of a single part. The strength of the buckle depends not only upon the composition of the housing structure and cam, but also on the composition of pin 20 and how pin 20 is attached to the housing.
Unlike the invention of Libecco, which is designed for a round elastic cord, my tension device can secure a serpentine article of any shape and made of non-elastic or elastic material. One reason my invention is more versatile is that my lock mechanism is not dependent upon protrusions but due to forces applied by the angled channel. In Libecco""s invention while the protrusions engage the cord under tension they also impede the movement of the cord for adjusting the overall length of the tie-down. The channel in my invention is smooth and the serpentine article easily slides through my invention for adjusting the tautness or length.
When detaching an elastic tie-down, it is safer to release the tension of the tie-down by sliding the tension device prior to unfastening the hooks. Because Libecco""s invention has protrusions holding the cord in place, it would be difficult to loosen his tie-down while under tension. With my invention it is easy to lengthen or shorten the tie-down while under tension.
The strength of a tension device is an important parameter when securing a load. The strength of the tension device can be limited by the grip on the serpentine article and the strength of the material of the device. The strength of the invention of Libecco is as strong as the protrusions in the channel that engage the cord. The strength of the invention of Plzak is the strength of the weakest component: the cam, the housing, or the pin that holds the cam. Since the preferred embodiment of my invention has no protrusions that engage the serpentine article and no component or moving parts, the strength of the preferred embodiment is limited by only the strength of the material from which the tension device is constructed, be it, plastic, wood, or metal.
The primary object of the invention is to provide a self-locking and adjustable tension device to change the tautness of a serpentine article while under tension.
Another object of the invention is to provide for a self-locking and adjustable tension device that easily secures a serpentine article shortened to any selected length and that the selected length is further adjustable.
Another object of the invention is to provide for a self-locking and adjustable tension device that will accommodate serpentine articles of different diameters and shapes.
Another object of the invention is to provide for a self-locking and adjustable tension device that has only one piece and thereby is as strong and as durable as the material from which it is constructed.
Another object of the invention is to provide for a self-locking and adjustable tension device for elastic and non-elastic serpentine articles.
Another object of the invention is to provide a self-locking and adjustable tension device that has no rotating parts so that there is no possibility of corrosion and malfunction due to moving parts.
Yet another object of the invention is to provide a self-locking and adjustable tension device that adjusts the length of a serpentine article simply by sliding the body of the tension device.
Still yet another object of the invention is to provide a self-locking and adjustable tension device in which the forces are evenly distributed across the body and the body does not tilt while under tension.
A further object of the invention is to provide an adjustable tension device that will adapt to multiple situations that has previously been fulfilled by several individual adjustable and non-adjustable serpentine articles. My invention obviates acquiring a variety of tension devices to prepare for unforeseen needs.
A Still further object of the present invention is to provide a self-locking and adjustable tension device with a loop that surrounds an object and exert circumferential force that can be applied and adjusted with one hand.
Other objects and advantages of the present invention will become apparent from the following descriptions, taken in connection with the accompanying drawings, wherein, by way of illustration and example, an embodiment of the present invention is disclosed.
In accordance with a preferred embodiment of the invention, there is disclosed a tension device that adjusts the length and tautness of a serpentine article comprising: a body, an angled passage through the body for passing and gripping the serpentine article, and a method of attaching one end of the serpentine article to the body to form a loop.